Abstract
The objective of this study was to determine the bone response of adult horses to exercise. For this purpose, 14 Arabian horses were selected and divided equally in two groups, a control group (CG) formed by animals that had never practised physical activity nor been tamed and an exercise group (EG) formed by athlete animals. Radiographs were obtained using a digital radiography system and penetrometer. The radiographs were stored and later processed to determine cortical bone thickness using the ProgRes® Capture Pro 2.5 (Jenoptik, Germany), cortical bone density using Adobe Photoshop CS6 (version 6.0, Adobe Systems Inc., San Jose, CA, USA), and trabecular bone density using the Image-Pro Plus 4.1 (Media Cybernetics Inc. Silver Springs, MD). The EG presented an increase in cortical bone density and thickness compared to the control. This adaptation of the cortical bone in the exercised horses is an important factor increasing bone resistance to exercise. These structural changes are related to a morphofunctional response by the bone tissue as a whole.

Key words: Adaptation, densitometry, equine, bone